1. Field of the Invention
The present invention relates generally to circuits for personal audio devices such as wireless telephones and media players, and more specifically, to circuits and methods that manage circuits within a disconnectable headset based on characteristics detected at the microphone terminal of the headset.
2. Background of the Invention
Disconnectable headsets are frequently used with wireless telephones, personal media players, and other devices that provide connections for the headsets. Recently, headsets have incorporated active electronics for such applications as ambient noise cancelling, and also include their own power source, typically a battery included within either the headset, or a dongle disposed along the headset cable.
As with other battery-operated equipment, when energy is not actually being used, e.g., when the headset is disconnected or the audio device is inactive, it is desirable to place at least a portion of the headset in a power-down mode in order to conserve battery energy. Further, battery-powered headsets typically include gain stages and have a higher input impedance, so open connections of a disconnected headset, or a connected headset that has not been properly configured with the device to which the headset is connected may generate audible noise.
Therefore, it would be desirable to provide a headset that provides power management of headset electronics without generating audible interference.